Driving mechanism for rotary switches



Jan. 16, 1951 Y. J; G. JUILLARD 2,538,004

DRIVING MECHANISM FOR ROTARY SWITCHES Filed April 29, 1947 i I E I A 2 I I 55 INVENTOR )4/55 J G. JU/LLH/PD ATTO R N EY Patented Jan. 16 1 951 DRIVING MECHANISM FOR ROTARY SWITCHES Yves J. G. Juillard, Paris, France, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application April 29, 1947, Serial No. 744,670 In France July 24, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires July 24, 1965 4 Claims. 1

This invention relates to improvements in driving mechanisms of the well-known electro-magnetic pawl and ratchet type with self-interrupter contacts for step-by-step rotary switches of the kind used in automatic telephone systems.

In rotary switches of a commonly-used type, particularly in automatic switching telephone equipment, rotation is caused by the action of a pawl, attached to the armature of an electromagnet, said pawl acting on a ratchet wheel keyed to the wiper block shaft. For the purpose of obtaining oscillatory motion of the armature, and thus of the pawl, a contact is inserted in the energizing circuit of the electromagnet and operated by said armature in such a manner as to open said energizing circuit when required and cause, through a spring, the return of the armature to its initial or rest position. During a complete back and forth excursion of the armature, the pawl causes the ratchet wheel to rotate one tooth and the wipers to move ahead one step.

In the equipment commonly in use, the opening and closing of the contact inserted in the energizing circuit of the electromagnet takes places at one and the same position of the armature. Therefore, in practice, operation is possible only thanks to the mechanical inertia of the moving parts and the self -inductance of the electromagnet winding,

which requires delicate adjustments which hold good only within narrow voltage limits.

Various solutions have been offered to improve reliability of operation, particularly through methods making it possible to have the opening and closing of the electromagnet energizing circuit take place at different positions of the armature, in order to allow a sufficient stroke of said armature, for the purpose of improving reliability of the moving of the pawl on from one tooth to the next. However, while the solutions offered permit improved operation, said operation still remains very sensitive to the variations of the energizing voltage.

The object of this invention is to provide a driving mechanism for the wipers of rotary switches in which the opening and closing of the contact inserted in the energizing circuit of the electromagnet are made dependent, on the one hand, on the position of the armature at the end of its attraction stroke and, on the other hand, on the position of said armature at the end of its release stroke. Thus, said mechanism, by means of simple adjustments, makes it possible to have perfectly satisfactory and reliable operation, this holding true for all energizing volages capable of attracting the armature of the electromagnet, said 2 operation no longer depending only on the inertia of the moving part and self-inductance of the winding.

A characteristic of the invention is to be found in the fact that it makes use, for actuating the contact inserted in the energizing circuit of the electromagnet, of an auxiliary arm associated with said electromagnet, and operated b the driving mechanism of the rotary switch at the end of the attraction and release strokes respectively, being maintained attracted or locked throughout the attraction stroke and released throughout the release stroke.

The principles on which the invention rests and various other characteristics Will be made clear by the description which follows, which will be given in relation with the appended drawing in which:

Figure l is a side elevation of the driving mechanism for a rotary switch of the ten position type. To make the figure clearer, the wipers and bank contacts have not been shown.

Figure 2 is a top view of the mechanism illustrated at Figure 1.

Figure 3 is a front elevation of the mechanism shown on Figure 1.

Figure 4 is a detailed view showing the arrangement for operation of the auxiliary arm by the driving mechanism of the switch.

A bell crank-shaped yoke or pole piece 28 is attached to platen I by screws 35 and 3S. Said bell crank 28 carries electromagnet 21, attached to it by a screw 29. Bell crank 28 alsocarries, attached by screws 3| and 32,,and parts such as 31, a shaft ll, about which armature In of the switch-driving mechanism can pivot. Part 28 completes the magnetic circuit for the assembly constituted by electromagnet 2'! and armature Ill.

The armature ii) is attached, by screw 38, to one of the extremities of a leaf spring 9, the other end of which is maintained in a block 39, riveted to pawl 8. Paw1'8, in turn, meshes with a ratchet wheel 4, keyed to sleeve 3, which can rotate freely about shaft 2, attached by nut 33 to frame I The moving brush block, not shown, is mounted on sleeve 3. Stop pawl 5 is attached to lug 40, made by folding over frame I; stop 6, for driving pawl 8,

also is attached to said lug.

Lugs M and 34, obtained by folding over frame I, have holes through which rod l2 can slide. The lower part of said rod, l2, carries a threaded sleeve l3, part I5 of which constitute a nut. Sleeve l3 can slide in the hole provided in lug l4 and carries the upper end 4| of pawl 8. The hole provided in end 4! has a larger diameter than sleeve [3, in order to enable pawl 8 to oscillate is-completed, armature i0 is attracted.

3 about the axis of [2. The upper part of rod I2 carries a spring 18 which seats, at its upper part, against lug 34, and at its lower end against nut I1. The adjustment of the tension of said spring can be effected by moving nut H which is then maintained in the position chosen by lock nut I6.

On the upper part of rod l2 (Figure 4) is screwed a sleeve 42 with a shoulder 43, this sleeve" passing by way of auxiliary arm 22 through an: opening 44 (Figure 2) and carrying a thread onto which are screwed nut 23 and lock nut 24.

Auxiliary armature 22 is connected. to yoke 28 by a screw 25, arranged to permit vertical pivotal movement of arm 22, and by aspring 26. A central perforation is provided in said auxiliary arm; for the head of screw 29.

At rest, the various parts occupy the positions shown on the drawing. Spring [8 presses down on rod I2 and said rod, by the action of nut 23, maintains auxiliary armature 22 in contact with yoke 28 In thatposition, insulating plunger 2|,

fixed to the end of auxiliary armature 22, forces moving contact 20 against fixed contact 191 The oircuitof. electromagnet 21, passing through said contacts, is thus closed.

When the driving circuit for the rotary switch It raises rod 12, compressing spring l8. Auxiliary armature 22 no longer is subjected to the action of'said spring H! but remains stuck to pole piece 28, through theaction of the lines of force of electromagnet i 'l. When pawl 8 has fallen into the following tooth of wheel 4, shoulder 43 (Figure 4) comes against auxiliary armature 2'2 and causes its release, which frees the spring of moving contact 2.0, whichrises, opening contact IL -20. The circuit of electromagnet 21 opens and armature I0 ceases to be attracted, whereupon the action of pring I8 has the effect of moving rod IZ'toward its lower position. Said rod actuates pawl 8, which causes the rotation of wheel 4 (which moves ahead one tooth). At the end -of the release stroke, nut 23 (Figure 4) carries with it armature 22 and brings it back to rest position against piece 28, contact l92'0 is closedanti the same -cycle of operations starts all over again throughout the duration of closing of the. driving circuit of the-rotary switch.

It will be noted that the adjustment of nut '23 along rod l2. (Figure 4) is so arranged that the motion of armature 22 takes placenear the end of the return of thev system to the rest position. Similarly, shoulder 43 comes against this armature only near the end of the attraction stroke of armature i0. tions, contact Iii-2'9 will be open only when pawl 8 will have moved on from one tooth to the next.

Said contact l'9--2D will be closed only when,

under the action of spring l8, pawl '8' will have caused wheel 4 to move ahead one tooth. This guarantees complete reliability of operation.

It will be seen that, in such .con'di- It would be possible, in order to increase the flux acting on auxiliary armature 22, to provide a certain number of holes in the horizontal part ofpiece-ZB.

It remains obvious that it would be possible to modify the shape and arrangement of the various parts, all embodiments making use of an auxiliary armature maintained locked by the flux of the electromagnet and acting on the contact inserted in the circuit of said electromagnet remaining within the scope of said invention.

I'claim:

1. Driving mechanism for rotary switches of the electromagnetic pawl and ratchet type comprising in combination a frame member, a yoke piece mounted on said frame member, an electromagnet mounted on said yoke piece, an armature pivoted to said yoke piece, a driving pawl operati'vely' connected to said armature and engaging the teeth of a ratchet wheel rotatably mounted on said frame member, an auxiliary armature resiliently supported on. said yoke *piece,contacts for closing and opening the circuit of said electromagnet, meanson said auxiliary armature for cooperating with said contacts, a link. member mounted in guides on said frame and. carrying at one end a stop member engaging said driving pawl and at the other end a stop member. engageillg said auxiliary armature and a spring on said link member.

2. Driving mechanism for rotary switches. of the electromagnetic pawl and ratchet type according to claim 1, wherein one of said contacts is spring mounted to be normally out of contact with the adjacent fixed contact andthe auxiliary armature carries a stop to engage said spring mounted contact.

3. Driving mechanism for rotary switches of the electromagnetic pawl and ratchet .according to claim 1, wherein said link member comprises a threaded ro'daaid the stop members comprise sleeve membersadjustably mounted on said rod.

4. Driving mechanism for rotary switches .of the electromagnetic pawl and ratchet type according 'to claim 1, wherein said spring is positioned. between oneof said guides and an Cadiustable stop on said link member arranged tor adjustingthe tension on said spring.

YVES J. G. J'UILLARD.

REFERENCES CITED The following references are of record in the file of thisv patent:

UNITED STATES PATENTS Number Name Date 1,653,888 Chaplin Dec..27, 1927 1,737,388 Redmond a-.. Nov. .26, 19-29 

